Rising above red-brick and wrought-iron surroundings, the 12-story box of concrete slabs supporting ribbons of green windows stands out like a steering wheel on a horse-drawn carriage.

Drayton Tower was billed as ''ultramodern'' when it opened in 1951. It had ''heat-absorbing'' windows and ''running ice water.'' Unlike any other apartment building in Georgia, it had central air conditioning.

Now its culture-clash design, marred by sooty stains and cracked windows, makes it a building Savannahians love to hate. Many see it as an eyesore of modern architecture that degrades the city's Old South charm.

But Drayton Tower now has something in common with its Victorian neighbors. The city of Savannah declared last month that Drayton Tower, at 51 years old, is a historic building.

''Absurd,'' says Lee Adler, one of Savannah's early preservation leaders.

''We were looking down on that very ugly building and wishing that it could be imploded,'' says Adler's wife, Emma.

Welcome to one of the hottest debates in historic preservation: How much of postwar modernism is worth saving?

The bold shift in architecture after World War II favored stark, often boxy, facades of unadorned raw materials. Half a century later, many consider them downright ugly.

But more preservationists are taking up modernism's cause for what it tells us about American life in the 1950s -- a time when American culture dominated the globe and people looked optimistically to the future, constructing buildings that looked ahead of their time.

To gauge modernism's worth using today's taste is too fickle, says Wendy Nicholas, northeast director of the National Trust for Historic Preservation.

''We are in the same place with regard to these modern buildings that cities were in regard to Victorian architecture in the '60s and '70s,'' Nicholas says. ''People of my parents' generation just railed against Victorian buildings as ugly, not worth saving.''

The idea of historic modernism isn't exactly new. New York's Lever House, a 1952 skyscraper of stainless steel and glass, was listed on the National Register of Historic Places in 1983 as an extraordinary example of modern architecture's international style.

But the debate is growing as more modern buildings reach their 50th birthday, generally the minimum age for historic status. And preservationists face the irony of saving architecture that their movement once considered its enemy.

''Many, many people became historic preservationists out of their hatred of modern design,'' says Diane Wray, a Colorado preservation consultant. ''They came to it out of a nostalgia for 19th-century architecture that they considered old and pretty.''

Wray listed Arapahoe Acres, the 1949 neighborhood of modernist homes where she lives, on the National Register in 1998 -- a first for a postwar subdivision. She's been defending modernism for the past 12 years.

''When I started pressing modernism, people with the state preservation board would attack me and say, 'I think this is the ugliest thing in the world,''' Wray says. ''To say that modernism has no value is really to degrade a whole generation of people.''

The National Trust has also taken up modernism's cause. Two modernist buildings made its list of this year's 11 most endangered historic places.

The 1958 Gold Dome Bank in Oklahoma City, topped with a geodesic dome 150 feet in diameter, needs $1.7 million in repairs. Its owner, Bank One, wants to demolish the building rather than restore it.

In Minneapolis, preservationists are struggling to save the 1963 Guthrie Theater, one of America's oldest repertory theaters outside Broadway. The Walker Art Center, which owns the Guthrie, wants to demolish the theater as it builds a larger replacement.

Minnesota's preservation office says the Guthrie's cultural significance makes it eligible for the National Register, though numerous alterations have ''compromised its architectural integrity.'' Ann Bitter, the Art Center's administrative lirector, says the old theater, if saved, would become an unused ''mausoleum.''

When it opened in 1951, Drayton Tower was meant to be a signpost to Savannah's future, a shining example of how technology made life easier at a time when many homes still had outdoor toilets.

Over the front doors jutted a canopy of reinforced concrete that seemed to levitate 15 feet over the sidewalk without supports. Elevators were self-service. Bathrooms had an extra faucet for ''running ice water'' from pipes cooled by the air conditioner.

''The building is one of the most unusual in apartment construction,'' the Savannah Morning News wrote on June 10, 1951. ''Savannahians never saw anything like it before.''

But Drayton Tower is no longer an upscale place to live. Cheap rent makes it popular with college students. Replaced windows don't match the original shade of green, giving the building a patchy appearance.

''It has to be the most reviled building in the city,'' says Robin Williams, huad of the architectural history department at the Savannah College of Art and Design.

Williams was among those who wanted some form of protection for Drayton Tower out of fear that someone might buy it just to tear it down. Now the owner must to apply to the city for permission to demolish it.

Williams says Drayton Tower is important because it has retained something most of its prestigious cousins in New York and Chicago have lost -- its shock value.

Modern buildings that once stood out in those cities were soon surrounded by similar modern structures. Downtown Savannah, meanwhile, remains a 19th-century city at heart.

''People come to Savannah and say, 'Ain't it quaint.' And you've got this stridently modern building sitting at its center,'' Williams says. ''It's like: I'm modern and I'm proud of it. ... It's a pure artistic statement, whether you like that statement or not.''